نتایج جستجو برای: airflow
تعداد نتایج: 8579 فیلتر نتایج به سال:
Realistic geometry of human upper airways from mouth to the end of trachea was reconstructed by implementing the CT-Scan images of a male subject. A computational model for analyzing the airflow in the airways was developed and several simulations were performed. To capture the anisotropy of the inhaled airflow in the upper airways, the Reynolds stress transport model of turbulence was used ...
We studied the impact of wall strain and surrounding pressure on the onset of airflow limitation in a thin-walled "floppy" tube model. A vacuum source-generated steady-state (baseline) airflow (0-350 ml/s) through a thin-walled latex tube (length 80 mm, wall thickness 0.23 mm) enclosed within a rigid, sealed, air-filled, cylindrical chamber while upstream minus downstream pressure, chamber pres...
BACKGROUND Chronic obstructive pulmonary disease (COPD) increases the risk of cardiovascular disease 2- to 3-fold. The factors responsible for this association remain largely unknown. METHODS AND RESULTS We analyzed data from participants, > or =50 years of age, of the Third National Health and Nutrition Examination Survey (n=6629) to determine whether C-reactive protein (CRP) and other syste...
RATIONALE Population-based studies have found evidence of a relationship between occupational exposures and Chronic Obstructive Pulmonary Disease (COPD), but these studies are limited by the use of prebronchodilator spirometry. Establishing this link using postbronchodilator is critical, because occupational exposures are a modifiable risk factor for COPD. OBJECTIVES To investigate the associ...
OBJECTIVES/HYPOTHESIS The most typical complaints of patients with nasal septal perforation (SP) are nasal obstruction, crusting, and recurrent epistaxis depending on the size and site of the SP mainly due to disturbed airflow patterns. The objective of the study was to determine the influence of differently localized SPs on intranasal airflow patterns during inspiration by means of numerical s...
Increasing lung volume improves upper airway airflow dynamics via passive mechanisms such as reducing upper airway extraluminal tissue pressures (ETP) and increasing longitudinal tension via tracheal displacement. We hypothesized a threshold lung volume for optimal mechanical effects on upper airway airflow dynamics. Seven supine, anesthetized, spontaneously breathing New Zealand White rabbits ...
Endoscopic surgery is performed on patients with chronic inflammatory disease of the paranasal sinuses to improve sinus ventilation. Little is known about how sinus surgery affects sinonasal airflow. In this study nasal passage geometry was reconstructed from computed tomographic imaging from healthy normal, pre-operative, and post-operative subjects. Transient air flow through the nasal passag...
Background & objectives: Chronic obstructive pulmonary disease (COPD) is characterized by irreversible airflow limitation and systemic inflammation which is also associated with pulmonary and extra-pulmonary complications. COPD Diagnostic Questionnaire (CDQ) is a valid questionnaire that is used to identify patients with COPD. The purpose of this study was to determine the relationship between ...
The pathological hallmarks of chronic obstructive pulmonary disease (COPD) are inflammation of the small airways (bronchiolitis) and destruction of lung parenchyma (emphysema). The functional consequence of these abnormalities is airflow limitation. Airway abnormalities and emphysema interact in a complex fashion in the development of airflow limitation in COPD. In an attempt to improve underst...
BACKGROUND Recent surveys report a surprisingly high prevalence of chronic obstructive pulmonary disease (COPD) worldwide. However, there is evidence that the application of a fixed ratio of forced expiratory volume in 1 s (FEV(1)) to forced vital capacity (FVC) may result in a relevant misclassification of airflow limitation. OBJECTIVES The definition of airflow limitation does have a signif...
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